Minor refactoring in AEAD code

Make it a little easier to add ChaCha20-Poly1305.

This also fixes the error code in case mbedtls_gcm_setkey() fails with
a status that doesn't map to INVALID_ARGUMENT.
This commit is contained in:
Gilles Peskine 2019-05-06 15:27:16 +02:00
parent ff2d200fa5
commit f7e7b01a25

View file

@ -3681,6 +3681,9 @@ static psa_status_t psa_aead_setup( aead_operation_t *operation,
case PSA_ALG_AEAD_WITH_TAG_LENGTH( PSA_ALG_CCM, 0 ):
operation->core_alg = PSA_ALG_CCM;
operation->full_tag_length = 16;
/* CCM allows the following tag lengths: 4, 6, 8, 10, 12, 14, 16.
* The call to mbedtls_ccm_encrypt_and_tag or
* mbedtls_ccm_auth_decrypt will validate the tag length. */
if( PSA_BLOCK_CIPHER_BLOCK_SIZE( operation->slot->type ) != 16 )
return( PSA_ERROR_INVALID_ARGUMENT );
mbedtls_ccm_init( &operation->ctx.ccm );
@ -3697,6 +3700,9 @@ static psa_status_t psa_aead_setup( aead_operation_t *operation,
case PSA_ALG_AEAD_WITH_TAG_LENGTH( PSA_ALG_GCM, 0 ):
operation->core_alg = PSA_ALG_GCM;
operation->full_tag_length = 16;
/* GCM allows the following tag lengths: 4, 8, 12, 13, 14, 15, 16.
* The call to mbedtls_gcm_crypt_and_tag or
* mbedtls_gcm_auth_decrypt will validate the tag length. */
if( PSA_BLOCK_CIPHER_BLOCK_SIZE( operation->slot->type ) != 16 )
return( PSA_ERROR_INVALID_ARGUMENT );
mbedtls_gcm_init( &operation->ctx.gcm );
@ -3704,6 +3710,8 @@ static psa_status_t psa_aead_setup( aead_operation_t *operation,
mbedtls_gcm_setkey( &operation->ctx.gcm, cipher_id,
operation->slot->data.raw.data,
(unsigned int) key_bits ) );
if( status != 0 )
goto cleanup;
break;
#endif /* MBEDTLS_GCM_C */
@ -3717,9 +3725,6 @@ static psa_status_t psa_aead_setup( aead_operation_t *operation,
goto cleanup;
}
operation->tag_length = PSA_AEAD_TAG_LENGTH( alg );
/* CCM allows the following tag lengths: 4, 6, 8, 10, 12, 14, 16.
* GCM allows the following tag lengths: 4, 8, 12, 13, 14, 15, 16.
* In both cases, mbedtls_xxx will validate the tag length below. */
return( PSA_SUCCESS );
@ -3844,15 +3849,15 @@ psa_status_t psa_aead_decrypt( psa_key_handle_t handle,
if( status != PSA_SUCCESS )
return( status );
status = psa_aead_unpadded_locate_tag( operation.tag_length,
ciphertext, ciphertext_length,
plaintext_size, &tag );
if( status != PSA_SUCCESS )
goto exit;
#if defined(MBEDTLS_GCM_C)
if( operation.core_alg == PSA_ALG_GCM )
{
status = psa_aead_unpadded_locate_tag( operation.tag_length,
ciphertext, ciphertext_length,
plaintext_size, &tag );
if( status != PSA_SUCCESS )
goto exit;
status = mbedtls_to_psa_error(
mbedtls_gcm_auth_decrypt( &operation.ctx.gcm,
ciphertext_length - operation.tag_length,
@ -3867,12 +3872,6 @@ psa_status_t psa_aead_decrypt( psa_key_handle_t handle,
#if defined(MBEDTLS_CCM_C)
if( operation.core_alg == PSA_ALG_CCM )
{
status = psa_aead_unpadded_locate_tag( operation.tag_length,
ciphertext, ciphertext_length,
plaintext_size, &tag );
if( status != PSA_SUCCESS )
goto exit;
status = mbedtls_to_psa_error(
mbedtls_ccm_auth_decrypt( &operation.ctx.ccm,
ciphertext_length - operation.tag_length,